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| United States Patent |
5,186,539
|
|
Manser
, et al.
|
February 16, 1993
|
Mixing kneader device and method for this production of dough,
particularly for pasta
Abstract
The new invention proposes a new method and a device for the production of
dough, particularly for pasta. The formation of dough from the dry raw
materials to the finished pressed products is effected in a very short
time in two stages. A raw dough is first produced in a 2-shaft mixing
kneader; this dough has a substantially complete protein structure. The
forming of the dough, including the mixing of the raw materials, takes
place by means of an interplay of kneading and shearing, but without
extrusion die pressure at the end of the first stage. In the case of
classic pasta, the dough which is produced in pieces by the short 2-shaft
mixing kneader is transferred to a long single-shaft press and pressed
with high pressure to form the desired shapes.
| Inventors:
|
Manser; Josef (Uzwil, CH);
Egger; Friedrich (Niederuzwil, CH);
Seiler; Werner (Zueberwanger, CH)
|
| Assignee:
|
Buehler AG (Uzwil, CH)
|
| Appl. No.:
|
508086 |
| Filed:
|
April 11, 1990 |
Foreign Application Priority Data
| May 25, 1989[CH] | 01968/89 |
| Nov 19, 1988[CH] | PCT/CH88/00219 |
| Current U.S. Class: |
366/85; 366/97 |
| Intern'l Class: |
B01F 007/08 |
| Field of Search: |
366/79,80,81,82,83,84,85,96,97,144,149
|
References Cited
U.S. Patent Documents
| 4423960 | Jan., 1984 | Anders | 366/85.
|
| 4474473 | Oct., 1984 | Higuchi | 366/85.
|
| 4534652 | Aug., 1985 | Stade | 366/85.
|
| 4752135 | Jun., 1988 | Loomans | 366/85.
|
Primary Examiner: Jenkins; Robert W.
Attorney, Agent or Firm: McAulay Fisher Nissen Goldberg & Kiel
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This is a continuation-in-part application of Ser. No. 426,787 filed Oct.
25, 1989, now abandoned.
Claims
What is claimed is:
1. A mixing kneader device for the production of raw dough, comprising: a
closed housing, a product feed inlet, a water feed inlet, a discharge
outlet, product flowing in a direction from product feed opening to
discharge outlet, and continuously working work elements in the housing,
said work elements including two cooperating work shafts, mixing and
kneading elements which include kneading screws alternating in said
product flow direction on each shaft with shearing elements therebetween,
wherein said product feed inlet and water feed inlet are disposed in a
first portion of the mixing kneader which is provided with screw elements,
said product feed inlet being separated from said water feed inlet, said
shafts lying in the same plane and said product feed inlet being arranged
perpendicular to the plane of said work shafts so that raw product is
grasped by said two work shafts and conveyed by positive conveying action
at every work cross section of said housing, said discharge outlet being
formed without extrusion die.
2. A mixing kneader device according to claim 1, wherein a first set of
kneading screws is constructed as a feed screw pair and the last set of
kneading screws is constructed as a discharge screw pair.
3. A mixing kneader device according to claim 1, wherein at least three
sets of screw pairs are arranged one after the other with a set of
shearing element pairs between them in each instance.
4. A mixing kneader device according to claim 1, wherein the work elements
are constructed as two shafts rotating in the same direction, wherein the
two shafts comprise a drive for less than 20.0 rpm, preferably for 20 to
100 rpm, and particularly preferably for 40 to 70 rpm.
5. A mixing kneader according to claim 1, wherein the ratio of the active
length L.sub.M to the inside diameter Di of the mixing kneader is in the
range of 3 to 7.
6. A mixing kneader device according to claim 1, wherein cooling and heat
exchange means are arranged in the stationary housing.
7. A use of the mixing kneader according to claim 1, for a pasta line for
the production of long or short pasta.
8. A mixing kneader device for the production of raw dough, comprising:
a closed housing, a product feed inlet, a water feed inlet, a discharge
outlet, product flowing in a direction from product feed inlet to
discharge outlet, and continuously working work elements in the housing,
said work elements including two cooperating work shafts, mixing and
kneading elements, which include kneading screws, alternating in said
product flow direction on each shaft, with shearing elements therebetween,
wherein said product feed inlet and water feed inlet are immediately
disposed in a first portion of the mixing kneader which is provided with
screw elements, said product feed inlet being separated from said water
feed inlet, and wherein the device is constructed as a low-pressure
two-shaft mixing kneader and a single-shaft pressing screw, product output
of the two shaft mixing kneader being fed to said single shaft pressing
screw.
9. A mixing kneader device according to claim 8, wherein the active length
of the single-shaft pressing screw is at least twice as long as the active
length of the mixing kneader.
10. A mixing kneader device according to claim 8, wherein the single-shaft
pressing screw, in its entirety, is at least 2.5 times longer than the
mixing kneader.
11. A mixing kneader device according to claim 8, wherein the mixing
kneader is arranged immediately above the single-shaft pressing screw with
a transfer shaft for the dough parts at said single-shaft pressing screw.
12. A mixing kneader device according to claim 8, wherein an air vacuum
connection is provided between the mixing kneader and the single-shaft
pressing screw.
13. A mixing kneader device according to claim 8, wherein a pressure pump
is coupled to the single-shaft pressing screw in the area of the extrusion
die for the production of products such as cannelloni or ravioli.
14. A mixing kneader device for the production of raw dough, comprising:
a closed housing, a product feed inlet, a water feed inlet, a discharge
outlet, product flowing in a direction from product feed opening to
discharge outlet, and continuously working work elements in the housing,
said work elements including two cooperating work shafts, mixing and
kneading elements, which include kneading screws, alternating in said
product flow direction on each shaft, with shearing elements therebetween,
wherein said product feed inlet and water feed inlet are immediately
disposed in a first portion of the mixing kneader which is provided with
screw elements, said product feed inlet being separated from said water
feed inlet, and wherein at least one dough rolls is arranged subsequent to
the mixing kneader.
15. A mixing kneader device for the production of raw dough, comprising:
a closed housing, a product feed inlet, a water inlet, a discharge outlet
and continuously working work elements in the housing, said work elements
including two cooperating work shafts, mixing and kneading elements being
arranged at the latter with positive conveying action in the entire work
cross section of the housing, said mixing and kneading elements being in
the form of opposing overlapping screw positions, said screw portions
alternating on each shaft with shearing elements therebetween, said shafts
lying in the same plane and said product feed inlet being perpendicular to
said plane, said shafts coupled to means for driving said shafts at a
speed which prevents adverse heating effects in the dough and wherein said
water inlet and feed inlet are separated and disposed in a first portion
of said housing containing said work elements.
Description
BACKGROUND OF THE PRESENT INVENTION
1. Field of the Present Invention
The invention is directed to a mixing kneader device for the production of
raw dough, comprising a closed housing, a product feed opening, a
discharge outlet and continuously working work elements in the housing.
2. Background Prior Art
A multitude of processing machines are currently being used for dough
making. Pasta makes up an increasing proportion of the foodstuffs prepared
via the dough die. The shaping is effected for the most part by means of
an extrusion process in which the viscous dough is pressed through the
press dies at high pressures of, e.g., 80 to 120 bar and cut to a desired
length.
Different binding forces are utilized for the shaping and for the
subsequent retention of shape. The so-called protein structure is the
classic binding. The protein structure is the net-like, spatial
interlinking of all protein cells which hold together the starch which is
in crystalline form. The protein structure can be changed and
re-structured as often as desired, but only as long as there is sufficient
water and the protein does not coagulate due to higher temperatures.
Vegetable albumin behaves in a way very similar to the hen's egg. When a
hen's egg is broken in cold water, it virtually retains its shape if this
is done carefully. When stirred briskly or beaten, a watery egg soup is
obtained which is colored by the egg. Its behavior is completely different
when the same egg is broken in boiling water. With a few seconds, the egg
takes on an almost bizarre outline shape and retains this without
mechanical intervention. In order to obtain a fine distribution of the egg
material, the entire contents of the egg must be beaten and stirred
vigorously immediately after being thrown into the boiling water. The
finely distributed egg particles thus retain their refined shape. In the
presence of heat, the coagulation of the egg mass takes place in the egg
immediately, within seconds, and is irreversible. All albumin-containing
raw materials processed with heat in the foodstuffs industry must take
these facts into account. This is true particularly in the case of
extruded products.
The temperature boundary value before the irreversible point is between
60.degree. and 80.degree. C.; that is, already below the actual boiling
temperature (that is, below 100.degree. C.). If a product mass is brought
into the range of 100.degree. C. or more during the mixing, kneading and
dough forming, only an insufficient protein structure is developed in a
subsequent shaping process, e.g. for classic pasta such as macaroni.
Over the past three to four decades, two independent foodstuffs processing
methods have come into use:
Process A
All products which are deliberately subjected to a boil-like or roast-like
change during the processing, particularly during the phase of dough
formation. Binder forces other than those of the protein structure are
utilized predominantly for the shaping of the dough parts. The
temperatures range from approximately 90.degree. to 100.degree. C. up to
200.degree. C. and 300.degree. C., respectively.
Process B
All products which do not exceed a temperature of between 60.degree. and
70.degree. C. during processing, that is, while avoiding irreversible
changes with respect to the protein binding. These are primarily classic
pastas which only undergo an actual thermal change (cooking through, etc.)
prior to consumption by means of the boiling process.
In practice, the so-called double-shaft extruder is widely used for Process
A. In technical circles, this is often designated as a screw conveyor pair
with the worst efficiency. The poor efficiency includes, above all, the
conversion of the corresponding drive output into friction heat. The
friction heat generated in the dough is one of the process parameters for
the heating and for the thermal treatment of the products. The product is
heated to 100.degree. to 200.degree. C. by means of the friction heat and
possibly subjected to a boiling effect with additional heating elements.
In Process B, especially for pasta dough and all corresponding special
doughs, any increase in the dough temperature above the range of
60.degree. to 70.degree. C., even only in places, must be avoided. As far
as is known by the present inventors, mixing troughs for mixing all raw
materials have been used almost without exception in process B in recent
times for dough formation for pastas, and subsequently one or more
single-shaft screws for building up the protein structure and for dough
formation and for building up the pressure of 80 to 120 bar required for
the final shaping. Thus, the temperature can not only be kept under
control, but remains substantially below the critical value of 60.degree.
to 70.degree. C., so that there is no irreversible damage to the product.
The simplest evidence for this is offered by the fact that cutting wastes
after the pressing of the products may be added again to the raw material
to be pressed without a loss in quality.
A substantial difference between Process A and Process B consists in that
the product throughput for pasta doughs and in pasta presses in larger
systems, respectively, is at present conventionally in the order of
magnitude of 500 kg to 2500 kg an hour. In comparable motor-driven drive
outputs for process A, the product throughput is several hundred kg per
hour.
A second difference consists, in addition, in the speed of the pressing
screw. In pasta presses, the speed is between 20 and 100 revolutions per
minute, in the two-shaft extruders for Process A, speeds of 200 to 300 rpm
and substantially more are generally used.
In the extrusion method according to Process A, a large portion of the
invested motor output is converted into heat and only a small portion for
the extrusion die pressure, and the smallest portion for the actual
forming of the dough. This explains the great discrepancy between the
ratio of motor output to throughput in pastas on the one hand and in
products using a boiling extrusion process with a familiar very low
throughput on the other hand.
Problem Addressed and Solution of the Present Invention
The invention addresses the task of providing and improving a device for
forming dough for unboiled products, that is, particularly for pasta
products, which satisfies the highest requirements with respect to hygiene
and which is simple with respect to construction in terms of the
apparatus.
The solution, according to the invention, is characterized in that the work
elements comprise two cooperating work shafts on which mixing and kneading
elements are arranged which have positive conveying action in the entire
work cross section of the housing.
To the surprise of all participating specialists, the proposed task was
solved in a faultless manner. The conveying and kneading action of a screw
pair is known. The kneading action can be intensified by applying two
cooperating screws instead of a single screw. Since a screw has a
conveying effect that is even gentle with the product when suitably
designed, it has been assumed implicitly up to the present that an
intensification of the kneading action is brought about as the static
pressure on the dough increases. Since an extrusion is delivered at the
outlet in the conventional cases of application, a desired twofold action
was seen in this fact, the kneading pressure on the one hand and the
extrusion pressure on the other hand. In many products, the simultaneously
produced heat reinforced an equally desired thermal effect, such as
gelatinization, cooking through, etc. It is known partly that a
double-shaft pair also has a very good mixing effect. However, the new
invention has departed from this only partially correct understanding to
the extent that the kneading effect is not dependent as part of a total
building up of pressure, but rather depends on a repeated intensive
kneading.
In an especially preferred manner, the work elements are two cooperating
work shafts which comprise kneading screws alternating, in each instance,
in the direction of the product flow, as well as shearing elements,
wherein the discharge outlet is constructed without extrusion die so as to
be ready for the extrusion die. The kneading screws preferably have a
positive conveying action and the shearing elements have a self-locking
action. Accordingly, there is an actual self-cleaning effect. The product
is also put through in the case of idling. In addition, the shearing
elements preferably have a shaping action which is effective along the
entire cross section. Accordingly, it is possible to achieve an ideal
kneading action with very low power consumption without building up high
pressure. A rolling effect is utilized between the screw pair on the one
hand and a cutting effect and crumbling of the dough, respectively, on the
other hand. When there is a good mixing of the components running
simultaneously as well as a homogenization, only that which is necessary
for the dough forming, particularly for building up a good protein
structure, is made and worked for the dough. In many tests, only a very
slight heating of the product was determined, so that the new invention
actually brings about a real technological advance without any detectable
disadvantage so far. Tests on industrial scale have further shown that the
energy requirement for forming the dough is approximately equal to that
required until now solely for the drive of the mixer shafts of the mixing
trough. Microscopic pictures confirmed that a good protein structure was
produced and also that no local heat damage occurred. The product is not
permitted any possibility of deviation for the dough forming, so that
every semolina kernel or flour particle is really bound in the dough. No
white spots could be detected on the finished products without special
means. Judging from the results, it is even presumed that the new
invention made possible a high quality not previously achieved with
respect to the dough formation A small clue may consist precisely in the
fact that no high pressure is built up for the forming of the dough. The
cutting elements actually cut the dough mass into pieces. This could
possibly be prevented under high pressure. The forming of dough with the
new invention is radically shortened in terms of time as well as with
respect to construction, which in relatively dry dough of 25 to 40% or 28
to 32% moisture, respectively, could not previously be achieved in spite
of research work lasting decades, but is first achieved by means of the
new invention.
The invention allows various other advantageous constructions. Thus, the
first set of kneading screws is advantageously constructed as a feed screw
pair and the last set of kneading screws is constructed as a discharge
screw pair.
It is particularly preferable that three or more sets of screw pairs are
arranged one after the other, each comprising a set of shearing element
pairs arranged between them.
In another advantageous design idea, the work shafts are constructed as
shafts rotating in the same direction, where the two shafts preferably
comprise a drive for less than 200 revolutions per minute, preferably for
20 to 100 revolutions per minute or, most preferably, for 40 to 70
revolutions per minute
In unproblematic cases of application, the work shafts can be arranged so
as to run in opposite directions. The advantage of this embodiment idea
consists in constructionally simplified requirements on the device and the
drive of the device, respectively, in terms of construction. Further, it
is also possible to apply more than two, e.g. three or more cooperating
work shafts with different kneading and conveying or locking actions. It
is recommended, in addition, to arrange cooling and heat exchanging means
in the stationary housing. In this way, the entire device can be heated to
optimum temperature for the processing at the commencement of production,
since a heating is effected at temperatures which are too low, since the
forming of the dough is impeded and proceeds more slowly at temperatures
which are too low, e.g. below 20.degree. C.
The connections for the raw material feed, particularly for semolina and
water, are directly into the first portion of the device which is provided
with screw elements and is constructed as a low-pressure mixing kneader,
wherein the latter is used in combination with a long single-shaft
pressing screw for the production of pasta. The single-shaft pressing
screw now assumes the part of homogenization in reciprocal action with the
high pressure build-up. It has been shown that an optimum distribution of
work which could not be achieved previously is now achieved between the
individual devices, of which there are still only two; since the forming
of dough is complete with respect to the protein structure in the
mixing-kneading device, a dough is formed which is moist but which is not
sticky to the touch, so that the transfer can be effected simply by means
of gravity without the risk of sticking or stopping. The outlet opening of
the mixing kneader is therefore preferably constructed so as to be open,
that is, without extrusion nozzles. The opening is preferably selected so
as to be smaller than the double-cylinder cross section, but larger than
the working cross section remaining open between the work shafts and the
double cylinders. The rearmost set of cutting knives crumbles the dough
and the rearmost set of screw elements, as seen in the direction of
product flow, obtains predominantly an ejecting function for the dough
pieces without a pressure build-up in the area of the discharge outlet.
The active length of the single-shaft pressing screw is preferably
constructed so as to be at least twice as long as the active length of
corresponding screw elements of the low-pressure double-shaft mixing
kneader, wherein it is especially preferable that the single-shaft
pressing, in its entirety, be constructed so as to be at least 2.5 times
longer than the low-pressure double-shaft mixing kneader.
For the highest pasta quality, an air vacuum connection is advantageously
provided between the low-pressure double-shaft mixing kneader and the
single-shaft pressing screw.
Further, it is possible to arrange a pump in the area of the extrusion die
of the single-shaft pressing screw for the production of products such as
cannelloni or ravioli.
The invention further concerns a method for the production of raw dough for
pasta dough with a liquid component of 25 to 40 percent by weight, which
is brought into the desired shape and cut in a subsequent pressing with a
screw press or the further processing by means of rolls, respectively.
Every participating specialist in the field of industrial pasta production
will be able to confirm that dough production has not undergone any change
for at least two to three decades, although annoying problems were known
with respect to cleaning and hygiene. It was not possible until now to
meet the demand for high quality of the finished product except with the
known method applied in practice. One of the prominent structural
component parts was the trough mixer, which was viewed as irreplaceable in
relation to the dough trough of commercial and industrial bread
production. Recently, it has been realized that the trough, which does not
fit the picture of continuous product flow, and the batchwise distribution
of the product flow, respectively, is still in full use in the bread
industry, since optimal conditions could not otherwise be provided for the
biochemical processes in the dough formation.
Inexpensive pasta loses a portion of the starch during boiling; this starch
is thrown away as boiling losses with the milky-white cooking water. Small
white specks are often detected in inferior pasta. They result for the
most part from individual flour or semolina particles which remained dry
during the dough processing and could therefore not be bound into the
protein structure.
The new method was assigned the task of simplifying the dough production,
particularly so that it can be better kept under control, wherein the
quality of the finished product must satisfy the highest requirements,
particularly so that an easy management of all hygienic considerations can
also be ensured.
The method, according to the invention, is characterized in that the raw
materials are mixed by means of a cooperating work shaft pair with
simultaneous positive conveying and are kneaded by means of repeated
kneading action to form a raw dough with a developed protein structure.
In another particularly advantageous design idea, the raw materials are
kneaded into an unpressed raw dough in a first stage by means of a
cooperating work shaft pair by means of continuous interplay of kneading
and shearing and, in a second step, the raw dough is homogenized in a
single-shaft press or brought into the desired shape via dough rolls under
high pressure or via rolls.
The new method, according to the invention, has allowed for the first time
to separate the dough kneading from the problem of shaping in the forming
of the dough (especially with respect to the products with low water
contents of under 40% or under 34%). As has been shown, the optimal
forming of dough can be effected in a much more efficient manner, since it
was realized that a genuine mechanical cutting process is only possible
when the parts to be cut can be spatially separated and are displaced. One
part must be able to recede from the other, which is not possible in a
compact dough mass which is under high pressure. Rather, in the compact
dough mass, the picture of the tough fluid mass is more accurate. One does
not speak of cutting with respect to liquids. However, the all-around
binding through the protein structure requires a frequent mechanical
displacement of individual dough parts, as well as a simultaneous
distribution of water which is as complete as possible.
The raw dough is preferably transferred from the first stage to the second
step without pressure. It is especially preferable that the raw dough be
thrown out in pieces from the first stage and transferred by the force of
gravity directly to the second stage for the formation of a closed
homogeneous dough mass.
In the area of the transfer, a vacuum is advantageously produced by means
of connecting the corresponding transfer space to a vacuum pump, so as to
avoid entrapped air in the shaped dough. The product can be processed in
this way continuously in the stage in less than 60 seconds with a product
temperature of 40.degree. to 70.degree. C., preferably from 40.degree. to
50.degree. C., and transferred into the finished form.
The invention is further directed to the use of the method for the
production of long or short pasta, as well as the use of the mixing
kneader for a pasta line for the production of long or short pasta
immediately prior to the pressing screw or with intermediate transfer
elements.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in more detail below with the aid of different
embodiment examples. In the drawings,
FIG. 1 shows a mixing kneader, partially in section;
FIG. 2 shows the interplay of the work elements of FIG. 1 in outline;
FIG. 3 shows a section II--II of FIG. 2;
FIG. 4 shows a variant of FIG. 1 in a schematic manner;
FIG. 5 shows a side view of FIG. 4;
FIG. 6 shows a preferred application of the mixing kneader for the
production of pasta;
FIG. 7 shows a conception similar to FIG. 6, but for the production of
products like cannelloni or ravioli;
FIG. 8 shows the interplay of the new mixing kneader with subsequent pasta
rolls;
FIG. 9 shows another embodiment form of the mixing kneader with direct
transfer of the raw dough to a single-shaft pressing screw;
FIG. 10 shows the angular assembly of a mixing kneader with single-shaft
pressing screw in a schematic manner;
FIG. 11 shows a variant of FIG. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference is made in the following to FIG. 1, which shows a new mixing
kneader 1, wherein the upper part of a self-enclosed housing 2 is
substantially omitted in order to illustrate the work elements 3 and 4,
respectively. The two work elements 3 and 4, respectively, comprise two
shafts 5 and 6, respectively, which rotate in the same direction and
rotate in the clockwise direction. The two shafts 5 and 6, respectively,
are alternately provided with a set of kneading screws 7, 8 and 9 and 7',
8' and 9', respectively, as well as with a set of shearing elements 10 and
11 and 10' and 11', respectively, in a corresponding manner, which is
wedged on the shafts 5 and 6, respectively, so as to be fixed with respect
to rotation relative to it, the latter being constructed as splined
shafts. The product is fed into the mixing kneader via a product feed
opening 12. The liquid component, e.g. water or egg soup, is likewise
admitted directly in the vicinity of the product feed opening 12 and
connection 13 are arranged in the area of the first screw 7 and 7',
respectively, which is constructed as feed screw pair 14, as can also be
seen in a simplified manner from FIG. 4.
Two screw pairs 8, 8' and 9, 9' and a kneading screw pair 11, 11' arranged
between the latter are shown in enlarged scale and in outline in FIG. 2.
The product is positively driven through the housing 2 by means of the
screws 8, 8', 9, 9'. In so doing, the product in FIG. 2 passes the
shearing element pair 11, 11'. Every set of shearing elements 11, 11'
comprises three polygon disks 15, according to the shown example, which
cut through the entire housing cross section in the manner of a toothed
wheel with three teeth but so as to 15 rotate in the same direction, which
housing cross section forms a horizontal 8. Because of the threefold
repetition of the polygon disks 15 and their unequivocally transverse
movement they provide a consistent cutting and crumbling effect for the
product which is moved through the screws primarily in the direction of
the shaft axis 5, 6. It has also proven very advantageous that the cross
section remaining open for the product only comprise thin-walled "cylinder
portions", i.e. the screw turns have only a small depth "T".
The outlet end of the mixing kneader 1 is shown in FIG. 3. The product
which is crumbled by means of the shearing elements 11, 11' is ejected in
crumbled form or in pieces through a free discharge outlet 16. A drive
gearing 17, not shown, for the two shafts 5 and 6, respectively, is
arranged on the side of the product feed opening, so that, in the shown
example, the two shafts 5 and 6, respectively, are supported so as to
overhang from the drive side. This step permits a simplified assembly and
disassembly of the work elements, particularly an easy cleaning of the
entire work space, in that e.g. the work elements can be removed in the
direction of the discharge outlet 16.
FIGS. 4 and 5 show the same mixing kneader as in FIGS. 1, 2 and 3, but with
a heat exchange system 20, wherein e.g. water which is influenced with
respect to temperature is admitted through an inlet sleeve 21 and can be
drained again through an outlet sleeve 22.
FIG. 6 shows a schematic arrangement for a particularly advantageous
realization of the new invention for the production of pasta such as
spaghetti, noodles, macaroni, etc. The dry component, semolina or flour,
is fed to the product feed opening 12 via a hopper 30 with metering device
31 and a feed screw 32 and in the initial portion or directly to the feed
screw pair 14, respectively. A quantity of water calculated exactly for
the metering output for the dry component is removed from a container 33
constructed as a balance and added to the dry component or to the feed
screw pair via a pump 34. Depending on the type of desired finished
product, additional egg soup, for example, can be added to the mixture via
a second container 34. However, it is also conceivable to store water of
different temperature in the containers and to regulate the partial
quantities to a predetermined water temperature. This is one of the steps
for keeping the temperature of the processing under control in extreme
situations, e.g. during interruptions, changes in throughput or the
starting process. A fourfold interplay of mixing or kneading and cutting
is shown in FIG. 6 analogous to FIG. 1. The product which is kneaded into
raw dough pieces is delivered from the free discharge outlet 16 directly
into the starting area of a single-shaft pressing screw 36 via a fall
chute 35 by means of gravity. The single-shaft press comprises a pressing
screw 32 in a cooled casing 38. A die head 39 with an inserted pressing
extrusion die 40 is at the end of the pressing duct. The single-shaft
pressing screw is a special design of the extrusion, wherein a pressure of
e.g. 80 to 120 bar must be built up immediately prior to the extrusion die
in a distributor head 41 so that the dough mass, which is still very
viscous, can be pressed through the die openings. In contrast to the
functioning of the extrusion of the single-shaft screw press, the mixing
kneader is not an extruder. All elements of the production unit, as shown
in FIG. 6, are controlled and coordinated by means of a common SP control
42. The length ratio Lm of the mixing kneader to L.sub.E of the
single-shaft pressing screw is of interest, wherein the active length of
the work elements are compared (FIG. 7). It has been shown that the dough
homogenization with pressure build-up can be achieved in the most optimum
manner with a relatively long single-shaft pressing screw with a large
working length (L.sub.E). On the other hand, all tests with very long work
elements of the mixing kneader have surprisingly not shown any positive
effects besides a high power consumption and development of heat in the
product. The best results are obtained when the length ratio (L.sub. E) to
(L.sub.M) is at least 2:1. Length ratios of the single-shaft pressing
screw to the mixing kneader of at least 2.5:1 result from the construction
design in its entirety.
It is also interesting that the best values were achieved as a whole when
the active length L.sub.M to the inner diameter Di is in the range of 3 to
7 in the mixing kneader.
FIG. 7 shows the additional possibility of producing filled goods such as
cannelloni 52, ravioli 53, etc. The filling substances of meat, vegetable
or sweet components are removed from a container 50 and pressed into the
product directly via the corresponding duct system of the pressing head
and via a special pump 51.
FIG. 8 shows an additional interesting realization of the invention for
rolled pasta. The dough pieces falling from the mixing kneader are
transferred directly to a pre-calibrating roll 60 and the formed strip is
transferred directly to a calibrating roll 61. The strip of dough is
converted to a desired dough leaf form, first through a longitudinal
cutter 62 and subsequently through a transverse cutter 63, which dough
leaf form is brought to a storable water content in a subsequent dryer.
The invention can be used in a plurality of other special products, e.g.
for the production of flake pastry or for the breading flour production
for the production of the raw dough.
FIG. 9 will be referred to in the following. Water is metered directly into
the mixing kneader 11 via a line 70. The dry raw material components are
fed uniformly via a feed head 71. The dry raw material is moistened
already in the inlet area and intimately mixed and guided into the
repeated kneading 5 zone. The mixing kneader 11 kneads a crumbly dough out
of the raw product. When the outlet end 73 of the mixing kneader 11 is
free, dough pieces of e.g. 1 to 5 cm are formed, partly almost hand-size
pieces which give the impression of being friable and crumbly, similar to
the interior of a baked bread. If the outlet end is narrowed, a "sausage"
of similar character is shaped, but as a continuous shape. However, in
both cases, the crumbly dough does not yet have the character of a compact
homogenous dough. That is, if a piece of the crumbly dough is torn off,
the actual character of the dough can easily be determined by the
plastic-elastic and non-sticky property. A microscopic examination shows
that the crumbly dough at the outlet end of the mixing kneader 11 actually
already has the full development of the protein structure. However, since
this is a dry dough and the actual shaping press pressure of e.g. 80 to
100 or more has not yet been applied, this impression of an easily
crumbling dough is only apparent.
The formation of crumbly dough proceeds as follows: the raw materials water
and semolina or flour are fed into the inlet of the mixing kneader 11.
FIGS. 9 and 10 show the actual kneading body in a horizontal position,
that is in a view from the top. On the other hand, the inlet is shown from
the side, that is, in upright position. In other words, the kneading body
is shown tilted by 90.degree. into the upright drawing plane, which is
indicated by the drawing section lines 73. The raw material is grasped by
two work shafts 76 and 77, respectively, via the feed elements 74 and the
inlet zone 75, respectively, and is conveyed to the right, according to
arrow 78, into a first kneading zone 79.
A pair of revolving kneading screws 79' are arranged in each instance in
the kneading zone 79 on each work shaft 76 and 77, respectively. The two
work shafts 76 and 77, respectively, rotate in the same direction (arrow
80) and mesh with one another similar to two screw toothed wheels.
Accordingly, a twofold effect occurs: a conveying of the product (arrow
78) and a compression; a compressed mass is formed. This mass is now
pre-kneaded and kneaded in the first actual kneading zone by means of the
kneading screws 79'.
The kneading screws 79' can be constructed in such a way that they result
in an action which dams slightly but also conveys. The mass leaving the
kneading zone 79 is pressed through a shearing zone 81 into a second
kneading zone 82, likewise with positive conveying. The development of the
protein structure is concluded in the next shearing zone 83. Similar or
different kneading elements can be used alternately in part in the
kneading zone 83. On the whole, the action of the mechanical pressure and
conveying forces occurs in a very directed manner at relatively very small
dough portions, so that virtually no unnecessary pressure forces and
friction effects occur.
This is why only a slight increase in the temperature takes place compared
with earlier kneading devices. The dough mass is fed to a discharge screw
84 or guided through a corresponding discharge zone 85, respectively, at
the end of the kneading zone 83 and is fed via the outlet end 72 for
further processing. The shown 2-shaft mixing kneader has the particular
advantage that it works in a self-cleaning manner to a great degree.
Depending on the construction of the outlet end, the dough can be
discharged as dough pieces or, with slight narrowing and corresponding
pressure build-up, in strands.
Of course, various constructions can be used for the work elements acting
in the individual work zones, particularly with respect to the kneading
and working elements, e.g. perforated disks, resistance bodies directed
from the outside to the inside, pins, etc.
In the embodiment form shown in FIG. 9, as in FIG. 11, a direct transfer of
the crumbly dough into the follow screw 86 takes place. The follower screw
can already be the actual pressing screw 87, as shown in FIG. 10. However,
it is important that the follow screw 86 has a greater conveying capacity
than the mixing kneader 11, so that an uncontrolled pressure build-up for
the kneader is prevented and so that the risk of an uncontrolled increase
in temperature is also prevented. The transfer of the crumbly dough from
the mixing kneader 11 to the follow screw 86 is effected in that the
conveying screw 87 cuts off the entering extruded dough.
FIG. 10 can also be understood in such a way that the shown individual
mixing kneading shaft symbolizes a shaft, or three or more shafts, in a
schematic manner.
The invention is explained in more detail in the following four examples.
EXAMPLE 1
Spaghetti, diameter 1.75 mm
______________________________________
Raw materials: 100% durum middlings
______________________________________
granulation smaller 0.350 mm
protein 14.1%/TS
ash 0.90%/TS
wet crude-gluten 34%
water, temperature 40.degree. C.
______________________________________
The raw materials, semolina and water, were fed continuously into the
mixing kneader via a metering with an output of 500 kg/h. The screw speed
was fixed at 42 rpm, and the cylinder was set at a temperature of
35.degree. C. After a dwelling or mixing and kneading time of 16 seconds,
the occurring dough pieces fell into the pressing cylinder in free fall.
The pressing parameters were adjusted as follows:
______________________________________
screw speed 20 rpm
cylinder temperature 28.degree. C.
head temperature 35.degree. C.
pressure 110 bar
vacuum 0.85 bar
______________________________________
The formed spaghetti were hung on rods after pressing and dried in a drying
system to a moisture content of 11.5% H.sub.2 O.
Quality Results
There is no difference between the spaghetti produced with the new method
and the traditional spaghetti in a purely external respect. The
transparency for typical water products from durum could be achieved. No
undissolved annoying white spots could be detected. Very good results were
achieved with respect to boiling quality. After a boiling time of 12
minutes, the "al dente" quality was achieved. Stickiness and boiling
losses were in the range of comparable commercial products.
EXAMPLE 2
Macaroni, diameter 5 mm.times.3.2 mm
______________________________________
Raw materials:
50% durum middlings
50% wheat flour
water
Quality of Initial Mixture:
granulation smaller 0.350 mm
protein 13.0%/TS
ash 0.70%/TS
product moisture 12.5% H.sub.2 O
______________________________________
The initial mixture of 50% durum and 50% wheat flour was fed continuously
into the mixing kneader by means of a metering with a capacity of 1000
kg/h and kneaded into a homogenous raw dough within 6 seconds. In contrast
to Example 1, the raw dough was not fed into the pressing screw in free
fall, but rather was transferred directly to the pressing screw according
to FIG. 9.
The kneader-pressing screw arrangement can be effected in any desired
manner. The transfer of the raw dough into the pressing screw was effected
in the low-pressure area without extrusion die pressure, i.e. the pressure
never exceeded 50 bar.
The pressing parameters were controlled as follows:
______________________________________
metering output 1000 kg/h dry
dough moistness 31% H.sub.2 O
mixing kneader
screw speed 60 rpm
cylinder temperature
30.degree. C.
L/D 1:7
pressing screw
screw speed 28 rpm
cylinder temperature
28.degree. C.
head temperature
45.degree. C.
pressure 105 bar
vacuum 0.9 bar
______________________________________
The macaroni was dried in a manner similar to Example 1.
Evaluation of Finished Products
Appearance, unboiled: transparent, smooth, without undissolved semolina
parts, color typical yellow
Boiling behavior: boiling with respect to shape, no crumbling, no surface
sliminess, no sticking
EXAMPLE 3
Egg horn-shaped pasta, diameter 5.times.3 mm, length 25 mm
______________________________________
Raw materials: 100% wheat flour
______________________________________
protein 12.5%/TS
ash 0.48%/TS
product moisture 13.1% H.sub.2 O
Egg quantity 3/kg flour
______________________________________
The raw materials were fed to the mixing kneader by means of metering with
a dry capacity of 700 kg/h and processed into a raw dough in the same
manner as in Examples 1 and 2.
A granulation device was attached to the outlet of the mixing kneader in
order to granulate the occurring dough pieces. The transfer was effected
in a free falling manner in vacuum on the pressing screw.
Production Parameters
______________________________________
metering output 700 kg/h
dough moistness 31% H.sub.2 O
mixing kneader
screw speed 50 rpm
cylinder temperature 40.degree. C.
L/D 1:7
screw profile:
a) inlet screws
b) shearing and conveying elements
c) kneading shears as discharge
screw pair
pressing screw
screw speed 24 rpm
cylinder temperature 28.degree. C.
head temperature 40.degree. C.
pressure 110 bar
vacuum 0.9 bar
______________________________________
The egg horn-shaped pasta which were cut at the extrusion die were dried by
means of shaking dryer, preliminary dryer and finishing dryer.
Evaluation Results
Raw horn-shaped pasta, unboiled: typically yellow, transparent, without
undissolved parts, smooth surface
Horn-shaped pasta, boiled: boiling time 10 min; water absorption--210%;
boiling losses--less than 5%; not sticky, smooth surface, stable with
respect to shape, typical taste, no annoying or negative changes in flavor
EXAMPLE 4
Spirals, two turns
______________________________________
Starting products: 100% Durum middlings, fine
______________________________________
granulation smaller 0.250 mm
protein 13.5%/TS
ash 1.00%/TS
product moisture 13.6% H.sub.2 O
______________________________________
The raw material was moistened with water to a dough moisture of 32%
H.sub.2 O and processed in the mixing kneader to form a raw dough. Instead
of direct feed into the pressing screw, the dough pieces were conveyed to
a converted pasta press by means of a conveying transporting means and fed
directly into a feed screw and subsequently pressed to form spirals.
Production Parameters
______________________________________
metering output, dry 800 kg/h
dough moistness 32% H.sub.2 O
kneader analogous to Example 3
shaper feed screw 31 rpm
pressing screw 24 rpm
cylinder temperature
25.degree. C.
head temperature 35.degree. C.
pressure 110 bar
vacuum 0.9 bar
______________________________________
The subsequent drying was effected analogous to Example 3.
Evaluation results
Showed the same evaluation criteria as in Example 3 in comparison to
commercial products. It was possible to achieve the quality of commercial
products.
While the foregoing description and drawings represent the preferred
embodiments of the present invention, it will be obvious to those skilled
in the art that various changes and modifications may be made therein
without departing from the true spirit and scope of the present invention.
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